Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, the submersible pumping system includes a number of components, including one or more fluid filled electric motors coupled to one or more high performance pumps. Other components commonly used include seal sections and gearboxes. Each of the components and sub-components in a submersible pumping system must be engineered to withstand the inhospitable downhole environment, which includes wide ranges of temperature, pressure and corrosive well fluids.
For prolonged operation in the downhole environment, it is necessary to seal various internal components of the pumping system from corrosive well fluids and debris. Although there are a variety of components within the pumping system that are susceptible to unwanted fluid migration, moving parts, such as rotating shafts, are particularly difficult to seal. To prevent fluid leaks around rotating shafts, designers often employ mechanical seals that fit around the outer circumference of a cylindrical shaft.
As shown in FIG. 1, Prior Art mechanical seal designs may include bellows 10, a coiled spring 12, a runner 14 and a stationary ring 16. These components cooperate to prevent the migration of fluid along a centralized shaft 18. The stationary ring 16 has an internal diameter sized to permit the free rotation of the shaft 18. In contrast, the elastomer bellows 10, springs 12 and runner 14 rotate with the shaft 18. The rotating runner 14 is held in place against the stationary face 16 by the spring-loaded bellows 10. The bellows 10 typically has a fold that allows its length to adjust to keep the runner 14 in contact with the stationary face 16 if the shaft should experience axial displacement. In the past, the bellows 10 has been manufactured from elastomers or thin, corrugated metal.
Limitations in presently available designs, however, can result in failures in the mechanical seal that allow well fluids to penetrate undesirable locations and to require costly repairs. After prolonged exposure to repetitive axial movement and elevated temperatures, the elastomer bellows 10 may degrade or slip from its intended position, thereby compromising the ability of the runner 14 to create a positive seal against the stationary face 16. It is to these and other deficiencies and requirements in the prior art that the present invention is directed.